Mistakes were made, my R34 Story

[MBS206]

Have you confirmed the throttle body goes to WOT (and stays there) during the run?

[Kinkstaah]

I mean, I can confirm the TPS is at 100%....

I can confirm when we installed the TB and setup the cable that the TB was indeed fully open at max pedal travel.. the same 'curve' (WRT MAP vs MAP) existed with the previous setup/TB/manifold as well...

No, we did not do a run with no intake connected.
I would love to go back in time to do such a run to rule out the intake.
It would have also been good to do a run with the airbox lid off.

There's a test there where increased IAT vs more available air could be a positive tradeoff. I remember taking the lid off my R34 Turbo setup back in the day and noticing a monster increase, even if IAT's did go up. Could be similar. Hard to test unless I find a very deserted road. 

[Kinkstaah]

On 31/05/2025 at 8:12 PM, MBS206 said:

Have you confirmed the throttle body goes to WOT (and stays there) during the run?

So, in the effort of pulling apart airboxes and testing enclosures to see if this aids in MAP loss at WOT I noticed:

1) The ducts up the OEM intercooler holes from the front bar help IAT drastically, whether the pod is shielded from the engine bay by an airbox missing a lid, or an airbox WITH a lid. Plus you get more induction sound without the lid. Having half the airbox (with no lid) acting as a barrier to the headers seems to help.

2) For shits and giggles I checked the TB.

This was full pedal travel.




This is actually full travel of the TB.
Photos aren't perfect, but there was definitely an amount of play in it and it wasn't against the stop.

After much swearing and adjusting the pedal, I realised that the cable is actually too long for the skyline pedal travel to fully articulate it. Having the pedal adjusted so WOT was actually hard open on WOT resulted in an idle of 3500rpm. As an aside, this was also the TPS registering at 3.1%.

I removed the above to give the pedal enough travel to actually fully open the TB. I now get a satisfying 'thonk' on full open and full closed which you can hear pumping the pedal as it hits the TB stops (with the bonnet open and intake back on).

Luckily for me, the screw screws into a raised metal boss under this plastic piece that is now acting as the new throttle stop. I've gained about 20mm (ish) of pedal travel and I can move it maybe a mm or two post open-thonk before it's hard against the stop.

After all of this I did a bit of road tuning because a 102MM throttle is sensitive. The difference between holding an 950rpm idle and instantly stalling is about 0.4% of TPS movement.

Will that help? I suppose it can't hurt. I set 'closed' point back to where it was, I can definitely feel the extra pedal travel that is needed to actually open the TB fully.

But this morning I dropped the car off at Paint Jail again, so who knows when this will re-eventuate out to see if it helps with the top of the dyno hitting a ceiling.

[MBS206]

Hopefully more pedal gives more powah!

Boo to paint jail, I want dyno comparisons!

[Kinkstaah]

I might be the only guy to be able to go back to the dyno like:

[The Bogan]

From my memory, which isn't that great, we did have issues getting the large throttle body on my old LS1 to play nicely at idle, first it would stall, then it would only idle at 2k rpm, then it would hang at 2k rpm for a few seconds and then drop and stall, then, finally, the best we got was it would hang at 1.5k rpm for a few seconds then drop to around 800 rpm

The tuner stated that large cable throttle bodies are a PITA, and if I wanted anything better than what we ended up with I would need a electronic throttle body and all of the aftermarket ECU stuff to run it

[Kinkstaah]

1 hour ago, The Bogan said:

From my memory, which isn't that great, we did have issues getting the large throttle body on my old LS1 to play nicely at idle, first it would stall, then it would only idle at 2k rpm, then it would hang at 2k rpm for a few seconds and then drop and stall, then, finally, the best we got was it would hang at 1.5k rpm for a few seconds then drop to around 800 rpm

The tuner stated that large cable throttle bodies are a PITA, and if I wanted anything better than what we ended up with I would need a electronic throttle body and all of the aftermarket ECU stuff to run it

They're notoriously difficult if you traverse forums... the 102TB and FAST102 are so bad that most people actively don't buy it unless they REALLY want that extra 1hp.

The idle stuff isn't really that hard. The cam is pretty manageable and while it acts like a larger cam the whole car actually drives smoother than before. I like to just tinker so if I can get 50rpm less variance or rule out situations where it does 'unexpected' things it's fun for me.

HOWEVER

If you just let a tuner give it a guess for a couple of hours and had no way/desire to test and tweak it yourself you'd spend a lot of money at the tuner or be pretty frustrated, that's for sure. But yeah. Drives great.

(then I drive partner's Civic Type R and I think.. well, more tweaking to do)

But for what it is (cam, TB, intake, manual etc) it does commute around really great once you figure out how the idle tables and GM's systems intend to work.

[Duncan]

Will be interesting to see if 100% of a 102mm throttle makes more power than 95% of a 102mm throttle....I would have thought a throttle that big was not the limiting factor in air getting in and as GTSBoy said earlier, somewhere (wastegates maybe?), the amount of additional air from 95-100% open is way less than say 25-30% open because it moves in a curve

[Kinkstaah]

Yeah - I found the same information too.. 30% open is like 85% of flow etc. So it's probably going to be minor if not completely imperceptible.

I also have a larger pod filter here, will swap that on and see if there's any difference. The hardest part is finding a place to uh, test this. It's quite noticable just how much having ducting to the otherwise completely open pod cools the intake temps down.

It's better boxed, or shielded but driving for 30 seconds really makes it plummet to near ambient temperatures. I recall in the past when I was a RB land and had a nice flowing airbox - 

- Then I took the lid off and put a pod there, and gained 9 psi of boost and about 60kw from the restriction I didn't know I had - with the controller at same duty cycle.

However finding people using over the radiator intakes having similar KPA drops at WOT on built setups makes me think there restriction could be the exhaust or potentially the headers. Either way though, there's no real estate to play with and nothing that can realistically be done about it.

The original dyno plot without the airbox, and the larger pod had a better curve. It was later I added the ducting and airbox, and a smaller pod to make it fit in there...

[Kinkstaah]

The car remains in paint jail. I am now pretty convinced that the whole "RB25 Airboxes are kinda limiting to ~300kw" could be a thing.

Also saw a good video from Engine Masters: (Sorry for FB link)
(https://www.facebook.com/watch/?ref=search&v=761771519471924&external_log_id=c10bcbb6-2c39-4ff3-9240-287e9921fde6&q=Cold Air Considerations)

Where they tested Pod Filter sizes and kept adding bends to a LS3 on an Engine Dyno to find if bends caused power loss. It's a good video worth watching - They did lose ~25hp from making an intake which had 3x90's and a 120 degree. They only lost maybe 1hp with a basic 90.

I feel that by sealing up my airbox I have:

1) Created the same restriction a stock airbox would have.
2) Created a very convoluted set of intake 'pipes' by forcing all the air through the ducts.

So I am pretty confident I'll be going full circle and have a huge hot air intake pod and actually see a benefit.

The air does *not* stay hot once it gets flowing, aided by the ducts, and the pod can then pull air from anywhere. All the posts of yore talk about the stock airbox costing 10-15kw at 300kw+ but you know what? I f**king would very much like that 10-15kw and I remember my own pod filter in engine bay experiences.

Turns out the GTT Reo and Headlight brackets really don't allow you to mount GTR items, no matter what the internet says. Various brackets have had to be made up to actually make it fit right for the front bar.

Also some idiot mounted a 3L Accusump right where the bumper wants to go, so that has had to be 'relocated' To where, I am still not sure, but it's supposedly mounted in the pictures and I can't see it.

[Dose Pipe Sutututu]

Install a MAP sensor pre and post throttle.

Best data you could have for NA, then play with the bends and/or air box and see how much of inflection is created at WOT on the plot.

[Kinkstaah]

soon

I also prefer the old look.
At least I have more clearance for wheels up front now.

[MBS206]

3 minutes ago, Kinkstaah said:

soon

I also prefer the old look.
At least I have more clearance for wheels up front now.

GTR front looks good.

If you don't like it, I'll swap you a rolling shell R33 for it. Give you a fresh base to start with.

[Kinkstaah]

Car is now back - I have the Nismo fender extensions on it too. Body place did a really good job with melding them to fit the sedan.


 

I'd take a photo of the whole car, but it's somewhat hard to do from where it's parked in the carport. The OEM'ness is growing on me. As is the desire to buy wheels - But it would be flat out dumb to buy maybe fitting wheels with minimum precision and rush to fit them before going on a Tasmania road trip. Probably better to do that one with OEM spec wheels on it.

I also bought a pod filter.

It is not OEM spec.

[soviet_merlin]

2 hours ago, Kinkstaah said:

The OEM'ness is growing on me.

Think of it as understated excellence.

Please post some photos when around Tasmania. Should be plenty of space there.

Did you change bodyshops? I'm pretty sure it hasn't been half a year since you dropped it off  

[admS15]

Nice fuse box breather vent mate. Lol.

Fender flare thingies look good. They enhance the car without being OTT. Nice addition, much like.

[Kinkstaah]

On 03/07/2025 at 1:35 PM, soviet_merlin said:

Did you change bodyshops? I'm pretty sure it hasn't been half a year since you dropped it off  

I did change bodyshops. The most recent place was very fast. I think the trick is to have smaller, simpler jobs. A front end repaint and some (extensive) sideskirt and fender stuff is a 'small cash' job for them. It was expensive but 'worth' it purely cause:

1) They did everything great
2) They did everything fast

Get what you pay for maybe?

Pictured: Very stock looking car from my very old phone. I did realise that oncoming traffic would probably be like "Oh look at this guy, commuting around in a GTR!" (until they see the side profile).

This is the sad state of my fender liners and front fitment with my current stock GTR sized wheels (18x9 +30)



This is how the rear sits with a 25mm spacer. I say 25mm because it's actually a 20mm spacer sitting on the studs which are ~30-31mm, and the wheels have a ~5mm cutout. So... this is very not safe to drive.


This is the other side.. .with a 22mm spacer. Yes, the studs are ~27mm. Yes they're different both sides. I spent a fair amount of time measuring.

This was the old pod setup behind the box in the past.

Old vs New Pod she tells you not to worry about:

 

Turns out I measured this pod filter pretty damn accurately which I was chuffed about.

I went for a ~3hr drive for 'testing' reasons up into Healseville hills. Believe it or not, the induction noise is the same between small and large pod. I guess it has more to do whether a pod is *present* or not, and the diameter of the pipe.

It does sound very decent in cabin though (and extremely 'smooth') - Though behind the car the exhaust noise is nonexistent now. So uh, it's all for the driver. I'm confident it has to be quieter than @Dose Pipe Sutututu's car. I should test it. Is there a way to do it with an app or something we can both agree on? (we are both very old men now competing for quietest car)

I've texted Trent at Chequered to book in to see some before/after. I can now twist the pod entirely out of the engine bay on the dyno to really rule in/out any intake restrictions. And/or remove the pipe entirely which I will probably do for testing reasons.

The logs show *maybe* a difference in ambient KPA vs Intake KPA at wot. But I'm talking the difference to -3/4 before to maybe -2/3 now. The tune is not wildly out or even changed at all.

The only takeaway I have is the car is on 17% ethanol as it's still got the fuel from the dyno in it. It's plausible that that tune would have resulted in the car erring on the side of being too rich (it was) and right now it seems to be bang on perfect or within -0.5% either side of target.

I was tempted to take it to a Drag day to see what MPH it would trap (and tune the car) but then I wouldn't have a number and a pretty line. I may do that after I re-hit the dyno, purely to go to LS1tech and shout about how their dynos are all very inaccurate while my low HP car traps the same MPH as cars with the same setup in the US, who make 375RWKW (supposedly).

It was safe to say Mr Mamo was not really happy with me posting the results yet. So I owe it to at least try the intake thing for my own sake and not besmirch people who want to buy a similar USA heads and cam setup and get disgusted that they make lower HP than simple bolt-ons which can be up to the "330rwkw+" kw region over there - Which here equates to about 270kw. (and runs the same 115-118mph)

[Dose Pipe Sutututu]

15 minutes ago, Kinkstaah said:

I'm confident it has to be quieter than @Dose Pipe Sutututu's car. I should test it. Is there a way to do it with an app or something we can both agree on? (we are both very old men now competing for quietest car)

Probably best way would be using a proper dB / SPL meter lol

Buy one and ship it from state to state to have a consistent test device lololol

 

[GTSBoy]

Cheapest Jaycar one is only $65.

[Kinkstaah]

19 minutes ago, Dose Pipe Sutututu said:

Probably best way would be using a proper dB / SPL meter lol

Buy one and ship it from state to state to have a consistent test device lololol

I'm gonna use the "Sound Meter" app from the Google Play Store and as close as I can bother to these procedures:

4. TEST METHOD FOR ALL VEHICLES EXCEPT PRE ADR83 IN-SERVICE GOODS VEHICLES AND OMNIBUSES

4.1 Microphone position

4.1.1 The microphone shall be directed towards the orifice of the exhaust outlet and shall be supported by a tripod or similar device not providing excessive acoustic reflection. The general requirements for positioning microphones are shown in the Appendix.

4.1.2 The nominal axis of maximum sensitivity of the microphone shall be substantially parallel to the test site surface and shall make an angle of 45 degrees ±10 degrees with the principal direction of gas flow from the exhaust.

4.1.3 In selecting the 45 degree alignment from the outlet of a motor vehicle fitted with two or more outlets, only the angle resulting in the microphone being farthest from any other outlet must be used. National Stationary Exhaust Noise Test Procedures for In-Service Motor Vehicles Page 3

4.1.4 The height of the microphone above the test site surface shall be equal to that of the orifice of the exhaust outlet ±25mm but shall not be less than 200mm above the test site surface.

4.1.5 The distance of the microphone from the exhaust outlet orifice shall be 500mm±25mm.

4.1.6 [Relates to vertical exhaust outlets]

4.1.7 For vehicles fitted with one exhaust outlet the microphone shall be placed so that the greatest possible distance is achieved between it and the vehicle.

4.1.8 [Relates to multi exhaust outlets]

4.1.9 [Relates to multi exhaust outlets]

TLDR:

200mm off ground
45 degree angle relative to exhaust flow
500mm from tailpipe exit.

(I probably won't use a tripod)

Here's a photo, cause I read the instructions wrong myself.